The field of the present invention is lubrication of two-cycle engines and specifically distribution of lubricant in two-cycle engines.
Conventional two-cycle engines employing lubricant entrained in the air-fuel mixture typically may employ a lubricating system such as illustrated in FIG. 6. The engine includes a crankcase 1, a cylinder 2, a piston 3, a connecting rod 4 and a crankshaft 5. The crankcase 1 and the interior of the cylinder 2 are connected by transfer passages 6 and 7. The crankshaft 5 is supported on a pair of bearings 8 and 9 in the crankcase 1. The bearings are in turn mounted in the crankshaft bore having sections 10 and 11.
In operation, entrained lubricant tends to adhere to the walls of the transfer passages and migrate downwardly toward the crankshaft. Such droplets of lubricant are represented in the transfer passages 6 and 7 at A. Lubricating holes 14 and 15 are provided strategically on the lower wall of the transfer passages 6 and 7 to collect and transport the lubricant into the shaft bore sections 10 and 11. The bearings 8 and 9 are adjacent the lubricating holes 14 and 15 to receive the lubricant passing therethrough. The lubricant also runs into the expanded portions 10a and 11a of the crankshaft bore sections to flow along the surface of the crankshaft 5 to appropriately wet the seals 12 and 13 located outwardly of the bearings 8 and 9.
The crankshaft 5 may also include a gear 16 formed on one side of the crankshaft to drive an oil pump through driving gear 17. This displaces the seal 12 laterally away from the bearing 8.
In such a conventional engine as is depicted in FIG. 6, pressure changes repeatedly occur within the crankcase 1 to enhance the flow of lubricant along the lubricating holes 14 and 15 and into the bearings 8 and 9. However, the conditions do not positively direct lubricant outwardly at the same time to the seals 12 and 13. This is particularly true if there is a substantial distance to the seals from the lubricating holes. This condition is aggravated by the presence of a lubricant consuming mechanism such as the gears 16 and 17 located between the seal 12 and the lubricant supply. This condition can lead to accelerated wear of the seals.